Organic solvent soluble benzyl ether of dextran



Patented Mar. 25, 1941 UNITED STATES PATENT OFFICE ORGANIC SOLVENT SOLUBLE BENZYL ETHEB F DEX'IRAN poration of Delaware No: Drawing. Application November 4, 1938,

Serial No. 238,856

6 Claims. (01160-209) This invention relates to coatings such as lacquer and the like.

It is an object to provide a coating which can be applied by brushing or roller coating, but

preferably by spraying, which will be characterized by very rapid drying, a coating that is tenacious to supporting surfaces, such as that of metal, and which is substantially inert to water, to certain acids, alkalis and alcohols and other 10 similar solvents, while it is soluble in certain cheap solvents which make it available as an industrial coating.

It is an object to provide such a coating that is soluble in acetone, cellosolve, dioxane, ethyl acetate, butyl acetate, diacetone, mesityl oxide and chloroform.

It is a further object to provide a coating that is substantially not inflammable either before coating or afterwards, and upon being coated when the solvent is dried or evaporated, it is substantially without inflammability.

It is a further object to provide such a lacquer coating which does not necessarily need any plasticizer or any resins in order to make it hard, im-

pervious to attacking agents, brilliant on its surface, and substantially clear as a varnish.

Heretofore in the art the most useful of the quick drying lacquer coatings have been nitrocellulose lacquer coatings made from low viscosity cellulose nitrate. Such a coating has been revolutionary in its effect in opening up the mass production of articles in industry because of its quick drying and spreading powers.

This prior art nitrocellulose lacquer has had several serious disadvantages. The first is its inherent inflammability, not only prior to being mixed with the solvent but after having been applied to a metal or other surface and the solvent evaporated. It has the further disadvantage of necessitating expensive plasticizers and resins in order to give it satisfactory adhering power and satisfactory brilliance.

The instant invention eliminates these disadvantages in that it will dry in approximately fifty per cent of the time now necessary for the drying of cellulose lacquers, and it is expected with further experience with the lacquer of the instant o invention that its present drying time will be very materially reduced by better methods of mechanical application. This advantage is a material one in industry in that it reduces the time of drying and thereby increases proportionately 10 the production rate of expensive labor, machinery and materials. The lacquer of this invention is further capable of being satisfactorily applied and satisfactorily adhering to such surfaces as metal without the necessity of the use of expensive 15 plasticizers, as it is very tough and inherently brilliant so that there is no necessityfor using resins. This does not. mean that plasticizing resins cannot be used with it but there is no necessity as exists with the present lacquers now 20 used in the art.

One of the principal objects of this invention is to provide a coating of this character that is inert to those things that normally affect an automobile body finish but which at the same 25 time would be soluble in such cheap solvents as acetone.

It is the object of this invention to provide a lacquer made of soluble benzyl ether of dextran.

Process of preparation In order to secure the lacquer of this invention, a solution of dextran is heated with benzyl chloride and sodium hydroxide for suitable periods of time and at suitable temperatures. There results from this process either a benzyl ether of dextran which is insoluble in acetone and other similar solvents or a benzyl ether of dextran which is soluble in acetone.

It has been shown that dextran has one of the following formulas:

l 1 ah) ln ln noon noon 0 noon noon n n I o n o noon no oo-o-o-o-o-omon n n o n no non on.-- on,----- n is apparent that the unit 01' the dextran molecule is a chain or tour anhydrogiucose residues Joined uniformly by giucosidic' linkages between the first and sixth of contiguous hexose units. According to Flor mula I, the fourth hexose unit carries a side chain or one anhydroglucose residue on carbon atom N0. 4; according to Fbrmula II, the side chain anhydroglucose unit is attached to-the sixth carbon atom and attachment is made to the rest of the molecule through carbon atom No. 4. It I I is not known how many of these five anhydroglucose units there are in a molecule of dextran but the presence oi the side chain separates it definitely in structure from such common polysaccharides as starch and cellulose.

when benzyl chloride is heated with dextran in the presence of sodium hydroxide the benzyl radical is substituted for the hydrogen atom in one or more of the hydroxyl groups in the dextran molecule (see Formulas I and II). The acetone-soluble product contains more benzyl radicals in each anhydroglucose unit than does the acetone-insoluble product. The soluble product is the one described herein.

The following are typical examples of the process. It will be understood that the proportions indicated are relative and approximate in the sense that further experience may indicate modifications of the proportions, depending on the type of production machinery employed and other factors. Modifications of temperature, time and pressure may, likewise, be desirable.

Example I To 30 grams of dextran dissolved in 100 cc. of water were added 46.5 grams of benzyl chloride (mole ratio of 2:1) and 17 grams of sodium hydroxide, and the mixture refiuxed at 105 to 110 degrees C. for six hours. Then 46.5 grams of benzyl chloride (total mole ratio of benzyl chloride to dextran, 4:1) and 17 grams of sodium hydroxide were added, and heating continued at 135 to 145 degrees C. for four hours. Soluble benzyl dextran was obtained.

Example 11 To 30 grams of dextran in 100 cc. of water were added 93 grams of benzyl chloride (mole ratio of 4:1) and 32 grams of sodium hydroxide, and the mixture refluxed with stirring for 0.5 hour at to degrees C. The temperature was then raised to and held at 135 to 140 degrees C. for 0.5 hour. Again it was slowly raised so that at the end of 1.5 hours it stood at 175 to 185 degrees C. where it was held for an additional 1.5 hours. The total heating period was three hours and the yield oi soluble benzyl dextran was good.

Example II! Thirty grams of dextran, 100 cc. of water, 47

3:1) and 10' gramsof sodium hydroxide were added, and the temperature raised slowly so that at the end of the first hour it stood at 175 to 185 degrees C., where it=wasmaintained for two hours. Soluble benzyl dextran results. v

I Example IV Thirty grams of dextran, 82 grams 0! benzyl chloride (mole ratio of 35:1), and 30 grams of sodium hydroxide were heated in an iron vessel, with stirring at 25 lbs. per square inch pressure for 0.5 hour. A soluble benzyl ether of dextran is obtained.

Example V Grams Dextran 30 Benzyl chloride Sodium hydroxide 40 Example VI It is found that heating under reflux should be conducted from approximately degrees C. to degrees C. for about six hours. This invention is not confined to such temperatures and pressures but this is a satisfactory procedure. It has been found thatthe addition to the foregoing Example V, after the supernatant liquid has been poured oil, oi a second batch of 90 grams of benzyl chloride, 40'grams oi sodium hydroxide, and 200 cc. of water, and the reheating oi the materials under reflux for an additional six hours gives a desirable product. The reaction mixture is steam-distilled to recover benzyl chloride and benzyl alcohol. This is a mole ratio of 7.5: 1 moles of benzyl chloride to dextran.

Example VII To 30 grams of dextran dissolved in l00 cc. of water were added 141 grams of benzyl chloride and 45 grams of sodium hydroxide, and the mixture refluxed at 105 to degrees C. for ten hours. The supernatant liquid was poured oil, the residue well washed with cold water, and extracted with 400 cc. of acetone. The acetone extract was then poured into cold water to reprecipitate the benzyl dextran, which was then dried in the oven at 90 degrees C. Thirty-six grams of benzyl dextran, representing a yield of 59 per cent of the theoretical amount of 63 grams was obtained. The

molecular ratio was 6 moles of benzyl chloride to 1 of dextran.

Example VIII To 30 grams of dextran dissolved in cc. of water were added 117.5 grams of benzyl chloride and 38 grams of sodium hydroxide, and the mixture refluxed for ten hours at degrees to degrees C. With the same purification procedure as was described before, 28 grams of benzyl dextran were obtained, a yield of 44 per cent of the theoretical. The molecular ratio of benzyl chloride to dextran in this case was 5:1.

Example IX To 30 grams of dextran dissolved in 100 cc. of water were added 93 grams of benzyl chloride and 32 grams of sodium hydroxide, and the mixture refluxed at 105 degrees to 110 degrees C. for ten hours. After the usual purification, a yield of 12 grams (19 per cent) of acetone-soluble, and 23 grams (3'1 per cent) of acetone-insoluble benzyl dextran were obtained. The molecular ratio of benzyl chloride to dextran was 4:1.

Example X To 30 grams of dextran dissolved in 100 cc. of water were added 23.5 grams of benzyl chloride (mole ratio 1:1) and 10 grams of sodium hydroxide, and the mixture heated at 105 to 110 degrees C. for six hours. At the end of this time, 70 grams of benzyl chloride (bringing the final mole ratio to 4:1 and 25 grams of sodium hydroxide were added and heating continued at to degrees C. for 4 hours more. Thirtyone grams (49 per cent yield) of acetone-soluble benzyl dextran were obtained.

Example XI To 30 grams of dextran dissolved in 100 cc. of water were added 70 grams of benzyl chloride (mole ratio of 3:1) and 25 grams of sodium hydroxide, and the mixture heated as before at 105 to 110 degrees C. for 6 hours. with the addition of 23 grams of benzyl chloride (bringing the total mole ratio to 4:1) and 10 grams of sodium hydroxide, the mixture was heated for an additional 4 hours at 135 to 140 degrees C. The yield of acetone-soluble benzyl dextran was 48 grams, or '76 per cent of the theoretical.

Example XII To 30 grams of dextran dissolved in 100 cc. of water were added 58.75 grams of benzyl chloride (mole ratio of 25:1) and 20 grams of sodium hydroxide, and the mixture heated with stirring for 3.5 hours at '15 to 80 degrees C. At the end of this time, 35.3 grams of benzyl chloride'(bringing the total mole ratio to 4:1) and 12 grams of sodium hydroxide were added, and heating continued at 135 to degrees C. for 0.5 hour, and then at 175 to 185 degrees C. for 2 hours. The total period of heating was 6 hours.

Example XIII To 30 grams of dextran in 100 cc. of water were added 93 grams of benzyl chloride (mole ratio of 4:1) and 32 grams of sodium hydroxide, and the mixture heated at 105 to'110 degrees C. for 0.5 hour. During the next half-hour the temperature was slowly raised so that at the end of the first-hour of heating it stood at 135 to 140 degrees C., where it was held at 175 to 185 degrees C., giving a total heating period of 4 hours.

Example XIV To 375 cc. of a culture medium containing 30 grams of dextran were added 4'? grams of benzyl chloride (mole ratio of 2:1) and 16 grams of sodium hydroxide, and the solution heated at '15 to 80 degrees C. for 0.5 hour with stirring. The temperature was then raised and held at 105 to 110 degrees C. for one hour. Forty-seven grams of benzyl chloride (making the total mole ratio 4:1) and 16 grams of sodium hydroxide were added, the mixture heated at 130 degrees to 125 degrees C. for 1 hour, and at to degrees C. for three hours.

The purification of the benzyl ether of dextran involves in general (1) steam distillation for the removal of benzyl alcohol and excess benzyl chloride, (2) maceration of the benzyl ether of dextran in water to remove water-soluble impurities and (3) complete removal of the water from the resulting product. Detailed methods of purlflcation may vary widely according to convenience. The purpose of purification is also to recover the benzyl alcohol and excess benzyl chloride in the steam distillate.

Solvents The following is a table giving the solvent characteristics of this product:

Two points of particular interest are to be noted in the table: (1) the insolubility of the benzyl dextran in water, alkalis, acids and the common alcohols, and (2) its solubility in the cheap commercial solvents, acetone, ethyl acetate and butyl acetate. By properly regulating the proportions of these solvents in the finished lacquer it is possible to obtain a wide variation in the rate of drying. It is comprehended within the term solvent or the use of the terms acetone, butyl acetate" or ethyl acetate," such other equivalent solvents as may from time to time be available in this connection. Under some circumstances it is found desirable to mix with such solvents others to bring the evaporation rate to such controlled rate as may be desired, as the rate of evaporation with acetone or ethyl acetate is very high.

The proportions of solvent and benzyl ether of dextran depend upon the type of coating to be employed. It has been found that 20 per cent solids and the balance solvents is a satisfactory proportion for some types of coatings.

The dextran itself is necessarily produced bac teriologi-cally, and the benzyl ether of dextran is therefore produced by the combined bacteriological and chemical action, as set forth in the 00- The method of producing the products recited herein is claimed in our co-pending case Ber. No; 238,853, iiled Nov. 4, 1938.

It will be understood that it is desired to comprehend within this invention such modifications as come within the scope of the claims and the invention.

Having thus fully described our invention, what 20 we claim as new and desire to secure by Letters Patent, is:

1. A new article or manufacture for use as a lacquer and the like comprising bensyi ether 02 dextran and an aromatic hydrocarbon solvent.

2. A coating composition comprising an aralkyl ether derivative oi dext-ran dissolved in a volatile aromatic hydrocarbon solvent.

3. A coating composition ccmprllng an an!- hyl ether derivative of dextran mixed with a volatile aromatic hydrocarbon solvent.

4. A liquid coating composition comprising a benzyl derivative of dextran and a volatile aromatic hydrocarbon solvent.

5. As a new article or manufacture a substantially inflammable liquid coating composition comprising an ether derivative oi dextran and an aromatic hydrocarbon solvent.

6. A coating composition comprising .benzyi ether oi dextran dissolved in a solvent mixture comprising toluol, ethyl acetate, butyl acetate,

and acetone.

GRANT L; STAHLY. WARNER W. CARLSON. 

